JRC JST-145 Proplem

[BG7KBH]

Hello, every body
I'm new to this Forum. Could anyone give me some clues about the problem of my new-bought TRX, JRC JST-145.

The TRX sometimes lost reciiving signal and reture to normal operation after hot-air blowing to the bottom of the inside box. and,

non-even dots made (usually longer time interval between two dots, just lisk: . . . . . . ., the 4th dot is a little delay than others).
here is the video:
http://hk.youtube.com/watch?v=XtDHu7kNT5A

[n8yx]

I'm going to take a guess...from the symptoms you describe, it sounds like the rig's PLL is unlocking.

The Kenwood TS440S and R5000 behaved similarly when their PLLs became unlocked; this due to an erratic VCO. Kenwood chose to use a hygroscopic (water-absorbing) potting compound as a vibration damper for some of the VCO components. Problems arose when the stuff absorbed a lot of water via high humidity - the components would corrode and ultimately fail.

A search of the Internet will reveal lots of info regarding the TS440S and R5000 equipment - along with the "fix" for their VCO problem.

For your JST, I would start by obtaining a service manual. Locate the main VCO board and see if the components are "potted". With the rig apart, direct the output of a low-temperature heat gun onto and around the VCO board...especially the potted pieces. Does the problem resolve itself? If so...you'll have to dig away the old potting compound with a dental pick or similar tool then possibly replace some components.

[BG7KBH]

Thank you very much John, I will trace the procedure step by step according to your instruction.